Signing is just the first step. Nations then have to follow through by ratifying the agreement. Only when 55 countries, representing at least 55% of world greenhouse emissions, have signed and ratified the agreement will it become binding under international law.

As 2016 continues to smash global heat records, there is a renewed sense of urgency among almost all governments. They now acknowledge that greenhouse emissions must be reduced rapidly if there is any hope of meeting the Paris Agreement’s goal of keeping global warming well below 2℃.

Australia’s government has confirmed that it will be represented at the ceremony, although it will be Environment Minister Greg Hunt rather than Prime Minister Malcolm Turnbull who will join world leaders in inking the deal.

Australia’s track record

Australia has signed previous climate treaties, but it has a mixed record in following through with its commitments.

Despite this sweetener, John Howard refused to take the logical step and render Kyoto legally binding by ratifying it. The Kyoto Protocol only entered into force in 2005, after Russia ratified the treaty. It was not until 2007, following the election of the Rudd government, that Australia finally ratified Kyoto.

In 2011 the Gillard government introduced an emissions trading scheme (with an initial fixed carbon price) to ensure Australia could meet its Kyoto commitments (and deliver deeper cuts over time, as by itself Kyoto has achieved minimal emissions reductions). But the Abbott government repealed this measure in July 2014 and replaced it with the Direct Action policy. This policy remains a work in progress and has not locked in the necessary emissions cuts to keep Australia’s goals within reach.

Australia’s actions since 2013 are clearly against the international tide. According to the World Bank, 40 nations and 23 subnational jurisdictions have adopted or are planning to adopt carbon prices.

The Turnbull government’s active and supportive participation in last year’s Paris climate negotiations signalled that, on the international plane at least, some bipartisanship has returned to Australia’s climate policy. The same cannot be said of the domestic front, where the major parties are still at loggerheads on the climate challenge.

Australia looks set to overshoot even its modest target of reducing emissions by 26-28% by 2030 relative to 2005 levels. And as commitments under the Paris Agreement will become stricter over time, with the deal requiring countries to ramp up their climate pledges every five years, Australia will be in an increasingly difficult and embarrassing position of having made promises it cannot keep.

This may set the scene for dithering by the Turnbull government, in much the same way as the Howard government held out against ratifying the Kyoto Protocol for a decade before finally proposing a climate policy when electorally it was already too late.

We know that to make a meaningful contribution to combating climate change, Australia needs a credible path to net zero emissions by 2050. To do this the Turnbull government must match its international commitments with effective laws and policies at home.

Legislating Australia’s climate targets, setting a national cap on emissions, and pricing carbon pollution are vital if Australia’s signature on the Paris Agreement is to mean anything at all.